DepthLOG Indonesia
Published: 02/12/2004
DepthLOG Indonesia
Published: 02/12/2004
An offshore gas well was producing water at an excessive level of 1,700 B/D and required immediate remediation. Because other depth-correlation techniques could not offer the real-time correlation and critical accuracy needed to perforate an interval within 10 ft of a water zone, the DepthLOG* coiled tubing service was used. DepthLOG correlation enabled isolation of the water zone and accurate placement of the new perforations, leading to increased produc-tion at reduced cost. A 60% increase in gas production to 800 Mscf/D from 500 Mscf/D was achieved. Water production was reduced from 1,700 B/D to 900 B/D, also leading to significant savings in surface handling and processing.
To shut off the water-producing zone, an inflatable packer was run on wireline through the 31â„2-in. completion and set as a bridge plug in the 5-in. liner. On the first perforating run, depth was correlated by tagging the packer; perforating guns were run on CT to just 140 ft above the packer and fired.
For the second and third perforating inter-vals 1,250 ft above the bridge plug, this simple depth-correlation technique did not provide sufficient accuracy. With a water zone as close as 10 ft above the anticipated perfora-tion depth, a memory casing collar locator (CCL) log was considered unacceptable. A CCL would have incurred additional costs, and it does not provide the accurate real-time correlation of the DepthLOG service.
The DepthLOG service does not require data cable, but communicates through pressure telemetry signals and provides a real-time CCL log at surface. Because balls and fluid are allowed to pass through the tool, a standard ball-operated firing head can be used.
The perforation string, mounted below the DepthLOG bottomhole assembly, was run into the well. The real-time CCL log available at surface allowed specialists to correlate depth against the baseline log and accurately position the guns to fire on depth.
The well was completed with 31â„2-in. pro-duction tubing set approximately 160 ft above the 5-in. liner. The well was initially produced from the perforations in the lower 5-in. liner.
Well characteristics
- 3 1/2-in. completion, 5-in. liner
- Producing 500 Mscf/D and 1,700 BWPD
- Upper gas zone within 10 ft of water zone
Job highlights
- Inflatable packer used to shut off lower water zone
- Lower gas zone perforated
- Upper zone correlated with baseline log and perforated on depth without introducing water zone
- Isolation of water zone increased gas production by 60%
